Washington -- In March 2005, former Orioles star Rafael Palmeiro famously shook his finger and denied under oath that he had ever used steroids. Six weeks later, he tested positive for stanozolol, a powerful steroid.
Had Palmeiro lied? The House Committee on Oversight and Government Reform saw reason to wonder but - after interviewing Palmeiro, his wife, and several other players and trainers - concluded it lacked evidence to recommend that he be prosecuted for perjury.
Three years later, the committee was in a similar position last week - this time in connection with Palmeiro's former teammate, Miguel Tejada - of suspecting a lie but appreciating how difficult such cases can be to prove.
The committee forwarded its suspicions about statements made by Tejada to the Justice Department in a letter, leading to the opening of an FBI inquiry.
Such cases pose daunting challenges, experts say.
"Perjury is difficult to prove," Gary Roberts, dean of the Indiana University School of Law in Indianapolis, said in an e-mail.
"Because it is a criminal case, the government would have to prove beyond a reasonable doubt that Tejada made a statement ... that could not be construed in any way except as a falsehood, and that he knew that it was a falsehood," Roberts said.
Tejada was questioned by committee staff at an Inner Harbor hotel as part of its Palmeiro investigation in August 2005. Palmeiro had told the committee that a tainted B-12 shot from then-teammate Tejada, now a Houston Astro, might have caused his positive test.
Tejada wasn't sworn in. But he could still be charged under a federal statute if found to have made "materially false statements."
According to interview excerpts released by the committee last week, Tejada replied "no" when asked whether he had ever taken steroids, androstenedione or any other steroid precursor.
Committee staff: Has there been discussion among other players about steroids?
Tejada: No, I never heard.
Committee staff: You never heard any of that?
Last month, former Sen. George Mitchell said in an investigative report that Adam Piatt - a former teammate of Tejada's with the Oakland Athletics - was asked by Tejada in 2003 whether he had steroids, and that Piatt provided the drugs. Two checks from Tejada were deposited into Piatt's bank account, according to the report.
But showing that Tejada wrote checks is not the same as proving he used steroids.
"Even if one believes the Mitchell Report's claim that Tejada did use steroids, proving it beyond a reasonable doubt is hard unless there is a smoking gun or the evidence is just overwhelming," Roberts said.
Tejada's attorney, Mark Tuohey, declined comment.
Prosecutors have recently won high-profile cases involving athletes accused of lying about steroids, including former NFL player Dana Stubblefield and former track star Marion Jones.
The committee seemed to have extra incentive to pursue Tejada. That's because committee chairman Henry Waxman, a California Democrat, and Virginia's Tom Davis, the committee's top Republican, believe Tejada's statements affected their ability not only to learn about Tejada, but also Palmeiro.
"We are especially concerned about the veracity of Mr. Tejada's statements because they materially influenced the course of the committee's investigation in 2005," Waxman and Davis said in their letter to the Justice Department.